I only briefly played around with 8 tracks, I think the main difference is songza has its playlists made exclusively by DJs, musicologists, respected music publications and the like, while 8track's playlists are user contributions (?)

Re the sneakers it's my wife I'm shopping for and I already do tons of thoughtful awesome stuff for her so its not a high risk venture. She just wondered out loud about new sneakers and said she wanted new chucks and something more interesting. She would be mad tho if I spent $500 on anything for her that wasn't a plane ticket somewhere she's never been